In the past, magnetoresistors were believed to be best formed from high carrier mobility semiconductive material in order to get the highest magnetic sensitivity. Hence, the focus was on making magnetoresistors from bulk materials that were thinned down or on films having sufficient thickness to exhibit a high average mobility.
We have found a new way to approach making magnetoresistors. We have found that if a thin enough film of indium arsenide is formed, and if an accumulation layer-like characteristic is provided in the film, an extremely enhanced magnetoresistor can be formed with such a material. We believe that an accumulation layer is inherently provided in an indium arsenide film when it is exposed to air. Tests indicate that the properties of the accumulation layer relevant to magnetic sensitivity can dominate over those of the remainder of the film, if the remainder of the film is thin enough.